Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$67.88	6.460%	$72.265	$72.27	$72.25	$72.30
Purchase #2	$13.30	7.192%	$14.2565	$14.26	$14.25	$14.30
Purchase #3	$73.91	13.526%	$83.9071	$83.91	$83.90	$83.90
Purchase #4	$21.71	7.304%	$23.2957	$23.30	$23.30	$23.30
Purchase #5	$182.60	4.798%	$191.3611	$191.36	$191.35	$191.40
Purchase #6	$170.30	5.439%	$179.5626	$179.56	$179.55	$179.60
Purchase #7	$46.89	6.285%	$49.837	$49.84	$49.85	$49.80
7 purchase totals =	$576.59		$614.4850	$614.50	$614.45	$614.60